The present invention relates to seat belt retractors and more particularly to a seat belt retractor assembly having a pretensioner (also called a belt tightening mechanism).
It is an object of the present invention to provide a seat belt retractor with a pretensioner that is compact in design, fast to engage with the spool of the retractor and one that provides for controlled loading of the spool during web rewinding.
Accordingly the invention comprises: a seat belt retractor having a rotationally mounted spool with a seat belt windable thereon and a pretensioner for winding the spool in a belt winding direction to rewind the seat belt upon the spool. The pretensioner comprises a rack and pinion mechanism activated by a pyrotechnic element, which causes a clutch assembly to change state from a disengaged mode to an engaged mode of operation in which the clutch assembly drivingly engages the spool. The clutch assembly comprises a clutch housing having provision to support a plurality of rotationally mounted clutch pawls. The clutch housing is received within a recess of the spool, such recess including a plurality of engagement teeth thereon, each of the clutch pawls configured to become column loaded between the spool and the clutch housing when in the engaged mode.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.